There are a number of applications which require accurate measurement from a start to a stop pulse, such as, for example, a TOA (Time of Arrival) pulse in a radar system. Where extreme accuracy has been required for such a measurement, typically a very high speed clock has been used to drive a counter. The accuracy has been limited by the resolution attained. The resolution of such a system is limited by clock speed (repetition rate), the upper limit of the counter rate. The resolution accuracy was never better than the period of the clock pulse repetition rate.